Enzymes have been used for numerous industrial, commercial and research purposes. In the laundry detergent field, however, they have only recently been included in various synthetic detergent mixtures, whether in dry, solid phase, or in liquid phase. Approximately twenty years ago, proteolytic enzymes (also referred to in this description as "proteases" or "proteinases") were first proposed for use in various detergent compositions, but since that time, virtually hundreds of patents and other references have been published, disclosing formulas of varying cleaning effectiveness. Illustrative of such detergent/enzyme mixtures is Zaki et al, U.S. Pat. No. 3,676,374, which discloses and claims an enzyme/detergent composition having a mixture of 2-35% anionic, and 2-30% nonionic surfactants, and 0.001-5.0% proteolytic enzyme.
Starting from about 1971, various cleaning compositions, whether laundry detergents, dishwashing detergents, dry cleaning chemicals, etc. were patented in which two or more different subclasses of enzymes, typically, proteases and amylases, were included in the formulas thus patented. Included among these patents are: Letton et al, U.S. Pat. No. 4,318,818; Maguire Jr., et al, U.S. Pat. No. 4,162,987; Kaminsky et al, U.S. Pat. No. 4,305,837; Richardson et al, U.S. Pat. No. 4,115,292; Place et al, U.S. Pat. No. 4,101,457; Pardo, Canadian Pat. No. 290,058; McCarty et al, U.S. Pat. No. 3,627,688; Siebert et al, U.S. Pat. No. 3,574,120 and Fehmerling, U.S. Pat. No. 3,513,071.
Furthermore, nothing in the prior art discloses, suggests or teaches that enzymes chosen from the same or similar, subgroup may become cooperative or synergistic. Also, the art does not disclose or suggest that combining enzymes within the same or related subgroup results in a stable mixture without addition of chemical stabilizers or other modifiers.
Bloching, et al, U.S. Pat. No. 4,122,999 (corresponding to British Patent Specification No. 1, 582, 200) propose a stabilized liquid enzyme cleaning composition having an enzyme preparation containing enzymes selected from proteases, amylases and mixtures thereof, a nonionic surfactant, an anionic surfactant, a monovalent alcohol, and an alkoxylated alkylamine (contended to act as an enzyme stabilizer). In one example (Example 10a in Table I), two similar enzymes are depicted in combination, namely, Maxatase.RTM. and Esperase.RTM..
In Table II of Bloching, et al, residual activities of the 20 examples are shown at 12 and 16 weeks. Bloching et al claims that for the examples (1-10) which have included in their formulas the alkoxylated alkylamine, substantial increase in stability occurs. However, Bloching, et al, do not show or suggest cooperative activity or increased stability for combined proteases in Example 10a. Further, the data disclosed in Table III is insufficient to enable any assessment of whether this isolated example of combined proteases has cooperative activity or stability. Thus, no specific benefit from the combining of these two proteases is shown.
There is thus no suggestion in the prior art of an improved enzyme system in cleaning applications which has enhanced enzymatic activity without addition of activators, chemical stabilizers or other modifiers. In cleaning and other applications, a concrete benefit would be obtained if enzyme activity were increased without increasing enzyme concentration, without changing the physical environment of the enzyme and without chemically changing the enzyme.